US3551333A - Surface sulfur recovery - Google Patents

Description

SURFACE SULFUR RECOVERY 3 Sheets-Sheet 1 Filed April 2, 1968 muses 0 23m m0 OR M D 0 T S T 5 F- X R E X JOHN A.SUTHERLAND RUEL C. TERRY ATTORNEY Dec. 29, 1970 STQDDARD ETAL 3,551,333

SURFACE SULFUR RECOVERY Filed April 2, 1968 3 Sheets-Sheet 8 .m .D Wm J TML l N R EwEY m v w um su TsT ACY E XNL WE xwR \J NQE ATTORNEY Dec. 29, 1970 Y STQDDARD ETAL 3,551,333

SURFACE SULFUR RECOVERY Filed Apriliz. 1968 S SheetS-Sheet s l I003 I002 4 4002 |oo| SULFUR '2 WATER":

lNVENTORS:

A RUEL C..TER RY 3 WWW Flui- ATTORNEY United States Patent 3,551,333 SURFACE SULFUR RECOVERY Xerxes T. Stoddard, Rosenberg, and John A. Sutherland and Rnel C. Terry, Houston, Tex., assignors to Allied Chemical Corporation, New York, N.Y., a corporation of New York Filed Apr. 2, 1968, Ser. No. 718,143 Int. Cl. 801d 37/00 U.S. Cl. 210-69 7 Claims ABSTRACT OF THE DISCLOSURE A process for the extraction of sulfur from ore at or near ground level in which the molten sulfur is passed through a bed in opposing direction to the flow of hot water.

This invention relates to a process for recovering sulfur from ore.

More particularly this invention relates to a process for recovering sulfur from ore which is located at or near ground level, as will be described in more detail hereinafter.

The mining and extraction of sulfur from ore (1) substantially below the ground and (2) located at or near ground level have been historically two separate problems of sulfur recovery.

In the case of mining and extraction of sulfur from ore mined substantially below ground level, a great deal of research and experimentation has taken place, with the Frasch process, as disclosed for example in U.S. Pat. 1,628,873, issued May 17, 1927 providing a basis for such sulfur extraction. On the other hand, in extraction of sulfur from ore located at or near ground level, a number of uneconomic or impractical, processes heretofore have been devised, usually so because of mechanical complication, cost, or inefficiency in the amount of sulfur extracted as compared to the amount of sulfur present in the ore. The extraction of sulfur from ore located at or near ground level has therefore been the subject of continued research.

The Frasch process of mining sulfur where it occurs in deposits substantially below ground level is discussed in detail in the patent to which we have previously referred. Generally, that process relies on the fact that agglomerating molten sulfur, which has become molten below the ground in the deposits in which it occurs (as a result of heat exchange with super-heated water which has been forced through these deposits), travels through the deposit under the action of gravity in a direction opposite to the movement of the lighter ore flushing water moving from the well bore through the deposit. The agglomerating or fusing molten sulfur arrives through the deposit at the point in the well bore where it can be carried up, as a result of the pressure differential, to an above ground location. We have devised a process and apparatus relying on the same principles of physical chemistry to effect the separation of the sulfur from the gangue.

Generally speaking, our process for extracting sulfur from ore at or near the ground surface is as follows:

Sulfur bearing ore located at or near ground level is usually stockpiled for sulfur recovery therefrom; such sulfur from deposits usually of, but are not limited to, the surface sulfur, spring, volcanic, hydro-thermal fumarole or solfataric types, including the presently poorly regarded, low-yield (540%) variety. The ore is then crushed and ground and then pumped (for example, as a slurry in hot water) or moved by a conveyer to a position for further treatment, to be discussed in detail hereinafter. The crushed and ground ore is mixed with hot water Patented Dec. 29, 1970 and, preferably, steam to commence melting of the sulfur deposited in the ore. The slurry of water and sulfur containing ore is then introduced into a fusion chamber under pressure. The molten sulfur, because of its tendency to agglomerate (as a result of the physical fact that it, like mercury, has an aifinity for itself) tends to join together as it melts at the elevated temperature, which has been reached in the elevated pressure in the chamber. The agglomerating molten sulfur passes downward through a bed in the chamber under the influence of gravity. Hot water is passed through said bed in a counter-current direction to the direction which the gangue (ore depleted of sulfur) and liquid sulfur tends to move. Since the molten sulfur is heavier than the water, the liquid sulfur passes through the bed in a downward direction while the water is passing upward through the bed counter-currently. As a result of preferential wetting, and the surface tension of the upwardly moving water, the gangue, even though heavier than water, is floated and washed by the upwardly moving water and separated, up to separation from the sulfur. The molten sulfur is then collected at a point below the bed for transmission to a storage area, while the gangue, the ore from which the agglomerated molten sulfur has been extracted, is carried by the water to be separated therefrom. The water may then be re-circulated to be reused in the process just described. As needed, additional hot water may be added to the process.

The invention will now be described in more detail with relation to the following drawings.

FIG. 1 shows a schematic illustration of the process for carrying out the invention;

FIG. 2 shows a schematic of a second embodiment for carrying out the process described; and

FIG. 3 is a detailed showing of the bed employed.

In the figures of the drawing, like numerals indicate like or equivalent structure throughout.

In FIG. 1, ore bearing sulfur 1 is shown at the extreme left awaiting processing for extraction of the sulfur deposited therein. Said ore has been mined at or near the surface, or in such a manner as to not allow for mining by the conventional Frasch process or its equivalent, already described. In the embodiment shown in FIG. 1, the ore bearing sulfur is fed to hopper 4 through use of, for example, conventional truck and ramp structure (shown schematically at 2 and 3 respectively). The ore is crushed to, for example, size, and ground to, for example, pass a 28 mesh screen in the hopper 4, again by the use of conventional structure, and loaded, for example, on an inclined conveyor 5. In the alternative to using an inclined conveyor the ground ore may be pumped as a slurry by a slurry pump or equivalent.

In this embodiment, the ore leaves the inclined conveyor at an appropriate height, of say feet, for reasons that will become apparent. Upon leaving the inclined conveyor the ore enters a hopper 6 which feeds into a water column 7, in which the ore is mixed with water from line 25 to form a slurry, said water at a temperature in the range of -200 F and preferably of about 200 F. The mixing of the hot water and ore may be effected by, for example, a Venturi jet mixer 8. It may be necessary to increase the wettability of the gangue as compared to the sulfur contained therein by introducing an acid, not shown, and to simultaneously neutralize the acidity of the slurry by the addition of a base, not shown, such as lime.

The pressure at the bottom of the column 7 is about 53 p.s.i.g. in the case of the drop of ore and water from the top of said column of 125 ft. previously mentioned. The slurry of water and crushed ore is moved by pump 9 through line 1002 toward fusion chamber 10, and preferably, mixed with steam (from line 1003 connected to steam generator 11) to commence substantial melting of the sulfur in the ore. Recirculating hot water, through line 12, and preferably, steam from the steam generator 11, from line 1003, introduced into the chamber serve to continue the melting of the sulfur deposited in the ore. As a result of the introduction of the hot water, and preferably the steam, and the fact that the slurry is under pressure in the chamber the temperature within the fusion chamber reaches about 260 to 280 F., and preferably about 270 F.

At this temperature, substantially all of the sulfur deposited in the crushed and ground ore slurry becomes molten, and as a result of its afiinity for itself, as previously discussed, tends to agglomerate or fuse.

The sulfur passes through the porous filtering bed 13 under the action of gravity. It may be directed toward said filtering bed by bafile 14. contemporaneously, hot water from the separator 27 is directed by pump 15 through line 16 upwardly through said bed 13.

Because the molten sulfur is heavier than the water, the sulfur tends to pass through the bed in counter-current direction to the movement of the water. The water floats and entrains the gangue (which does not pass through the bed) and removes it from cell 10 through line 17. Sulfur passing through the bed is collected at the bottom of chamber 10 and directed through line 18, which is valved at 19, to a collection pan 20, for example, for further filtering thereof or storage.

The gangue, moved by the water out of the chamber 10 through line 17 separates in desanders and desilters (shown schematically at 21) and is removed by suitable means, for example conveyor 22, to a place where it may be dumped.

Pump 23 draws the water from separator 21 and preferably directs it through line 24 for re-circulation to the Venturi jet mixer 8 through line 25 and through line 12 to the fusion chambers. Makeup and blend water is supplied through line 26. To adjust the temperature in line 25 to the desired temperature, for example 200 F., it is necessary to balance the temperature of the makeup blend water with the re-circulating water.

The wash water supplied through line 16 by pump 15 is, in this embodiment, taken from line 12 after filtering to remove silt in separator 27. Water may also be supplied from separator 27 to augment the heating of the sulfur and the ore in fusion chamber 10 before the agglomerating molten sulfur passes through the bed 13, said additional supply of water flowing through line 28.

One illustrative embodiment of the fusion chamber 10 and bed 13 is shown in more detail in FIG. 3. In said FIG. 3 a fusion chamber equipped with filtering bed is schematically shown. In those instances where applicable, like numerals in FIG. 3 to those used in FIG. 1 identify identical features.

The chamber 10 preferably is enclosed by a demountable head 1001 which has inlets with lines leading thereto to receive the slurry through line 1002 from pump 9 (of FIG. 1), the steam from steam generator 11 (of FIG. 1) through line 1003, the recirculating hot water through line 12, and the silty water through line 28. The chamber may be stainless steel clad and is preferably insulated. Mounted, preferably detachably for cleaning or other servicing, is a baflle 14 for directing the slurry toward the bed, the major portion of said baflle being mounted at an angle of, say 45 with the lower portion 2000 in the embodiment open to pass the slurry. The bed 13 consists of a top screen 1005 of relatively large openings, for example about A"; a straining bed 1006, composed, for example, of rock granules, such as graded gravel and quartz pebble about to 1%" diameter, thereunder; and a bottom screen 1007 of, for example about 1" diameter grid supporting the straining bed. A supporting head 1008 supports the entire bed 13 and is itself supported in any desired manner, say by trusses 1009. Hot water is introduced through the bottom screen 1007 upward through the straining bed 1006 through hot water line 16 and, for example, nozzles 4005. Water and gangue is removed from chamber through line 17. Molten sulfur is collected in pan area 1010 and taken from the chamber through line 18, valved at 19. A heating coil 1011, heated by steam or hot water preferably, may be routed through pan area 1010 to keep the sulfur molten. Overflow from the bed 13 may be collected in pocket 1013 just preceding line 17. The straining bed 1006 and screen 1005 thereabove are preferably inclined, as shown, to direct the water and gangue toward the outlet 17. A launder 1013 also may be provided at the lower end of top screen to collect the gangue and discharge it into the outlet.

As is obvious from FIG. 3, slurry entering the chamber will be deflected (and agitated) by batfie 14 to flow across the inclined top screen 1005. Steam and re-circulating water enter the chamber, as indicated. Hot water is directed upwardly through the bed 13. Agitation by said upwardly flowing hot water wash keeps the gangue particles in suspension as the agglomerating molten sulfur flows through the bed 13 by gravity, as diagramatically indicated in FIG. 3. The surface tension of the upwardly flowing water acts both to float off the gangue and to purify the sulfur as coalescence takes place, or where coalescence has taken place. Surface active agents added to the water may be used to further control the surface tension of the water, if desired.

Steam jets, 2001 and 2002, may be included in the chamber and at the discharge (line 17), respectively, to insure that the ore will not hang up below opening 2000 and plug up the discharge line 17.

The chamber 13 shown in FIG. 3 is illustrative of the type of pressure vessel with bed necessary to accomplish the objectives of our invention. Structural details of said chamber may be altered. For example, but not shown, the baffle may be conical or the overflow and gangue collecting apparatus may be constructed completely around the perimeter of the bed 13, with the bed not inclined as shown in FIG. 3. Preferably the chamber and other equipment should be made of or lined with corrosive resistant material.

The process illustrated in FIG. 2 in most respects is similar to that shown in FIG. 1, and employs chambers of the type described with relation to FIG. 3. In the manner in which it is similar, the functioning thereof is apparent from the description with relation to FIG. 1 and description will not be repeated.

An alternate manner of feeding the sulfur ore to the hopper is shown in FIG. 2, as compared to FIG. 1. In FIG. 2 a belt conveyor 200 is shown diagrammatically as transporting ore from the stockpile to the hopper.

As previously discussed, one alternate way to the inclined conveyor shown in FIG. 1 of moving the ore to the fusion chamber is by pumping. In FIG. 2 the ore in the hopper 4 is again crushed and ground. The sulfur containing ore is then mixed with water, flowing through line 201, at a temperature in the range of about 175-200 F. and preferably about 200 F. Again, a Venturi jet mixer 400, for example, may be utilized to introduce the slurry into mixing chamber 202. The slurry of ground ore and hot water is then pumped by a pump 203 through line 204 to the fusion chamber assembly. The line 204 is placed under pressure, for example, as the result of the use of a barometric leg 205 raised to an elevation similar to that described with relation to FIG. 1 and having a conventional overflow device 206. As described with relation to FIG. 1, steam is preferably added to the slurry of ground ore and hot water, as through line 207, to commence the substantial melting of the sulfur, the steam being provided by steam generator 11, for example.

In FIG. 2, there is shown two fusion chambers 10 and 10. The chambers 10 and 10' function alternately in the same manner as described with relation to FIGS. 1 and 3, and are illustrative of a manifold arrangement. As a result of employing the two fusion chambers 10 and 10, one

chamber may be cleaned or regenerated while the other is in service.

In the manner described with relation to FIG. 1, sulfur is removed from the bottom of the fusion chamber in operation (through line 18 or 18') which is valved at 19 or 19', respectively. The wash water, which moves counter-currently through the bed 13 or 13', is introduced through line 16 or 16' from Wash water pump 15 while the tailings which are removed from chamber 10 or 10' by the wash water exits through line 17 or 17' to a similar separating device 21 to that described in FIGS. 1 and 3.

In a like manner to that described in FIG. 1 Water is re-circulated through lines 24 and 20 1 to be mixed with the ground ore to form the slurry and to be supplied to the fusion chambers through line 12 and 12'. Once again, in FIG. 2 blend and makeup Water may be added through line 26 to make up for water lost in the process.

As shown, the tailings may be disposed of by engaging them in a slurry as the result of, for example, addition of water through line 210 and pump 211.

Steam may be added to the fusion chambers, as well as to the slurry directed toward the chambers by directing steam from the generator 11 through lines 207, and 212 to the chambers 10 and 10'.

Apparatus for recording temperature and pressure, located as shown in FIG. 2 at 4001 and 4002, respectively may be located in the equipment shown in the figures as desired. For purposes of illustration, valve structure is shown in FIG. 3 at points at which direction of flow may be alternative. It is emphasized that the incorporation of suitable valve structure at the necessary points according to mechanical design is a matter within the skill of one versed in the art.

As a result of the re-circulation of the water described, our sulfur extraction process has a high thermal efficiency. Heat added to the water in the fusion chamber, for example by steam injection results in the high temperature in the chamber, which is under pressure, and allows the water to be re-circulated without additional re-heating. Furthermore, the process is continuous, without moving parts in the fusion chamber, and provides for a high recovery of sulfur from the ore, as much as 99% of the sulfur deposited in the ore being extracted, and is particularly adaptable to low grade sulfur ores. Since it is a continuous process, relying on the physical principles utilized in the Frasch process for separation of the agglomerating sulfur from the ore, it is highly economic and elficient.

Although we have described, for the purpose of illustration, several embodiments of our invention it is not our intention to be limited by the details of such description but rather it is intended that the invention may assume many different embodiments within the scope of the following claim protection.

We claim:

1. A sulfur extraction process comprising the steps of mixing sulfur bearing ore with hot water to create a slurry, introducing said slurry into a closed chamber containing a filter bed, introducing steam under pressure into said chamber with said slurry, maintaining said chamber under pressure so that the temperature of the environment within the chamber rises to a level consistent With melting of substantially all the sulfur, passing molten sulfur through said bed, passing heated water into the chamber counter-currently through said bed to movement of said molten sulfur through said bed, washing and suspending said ore from which the sulfur has melted in said heated water after said water has passed through the bed, removing molten sulfur which has passed through said bed from the chamber, and removing from said chamber said ore from which the sulfur has ben melted with said last mentioned water.

2. The process as set forth in claim 1, including the steps separating said last mentioned water from said ore after removal from the chamber, and re-circulating said last mentioned water.

3. The process as set forth in claim 2, including the step of filtering at least a part of said re-circulated water to remove solid material, and passing said filtered water through said bed in said counter-current direction.

4. The process as set forth in claim 3, further including the step of heating said slurry by adding steam under pressure thereto before it is introduced into the chamber.

5. The process as set forth in claim 4, further including the step of deflecting the slurry in the chamber upon its entry therein in order to agitate it and direct it toward the bed.

6. The process as set forth in claim 5, further including the steps of screening the molten sulfur passing through said bed consecutively by an upper screen, a porous filtering bed, and a lower screen.

7. The process as set forth in claim 6, further comprising the step of blending makeup water in said re-circulating Water.

References Cited UNITED STATES PATENTS 337,459 3/1886 Thornton 210-183 2,044,214 6/1936 Jones 210-69 2,088,190 7/1937 Du Pont 23270X 2,746,846 5/1956 Gruenewald et al. 23270X 2,750,000 6/1956 Williams et al. 210-71X 3,072,463 1/1963 Owens, Ir. 23270X 3,080,220 3/1963 Lagatski 23270X 2,237,711 4/1941 Morgan 210275X 3,337,054 8/1967 Sauer 210-266 JOHN ADEE, Primary Examiner US. Cl. X.R.

Images